JP3040378B2 - Method for producing fluorine-containing random copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a process for the preparation of novel fluorine-containing random copolymer.

[0002]

2. Description of the Related Art Conventionally, tetrafluoroethylene (hereinafter abbreviated simply as TFE) has been used as a fluorine-containing resin having excellent chemical resistance, heat resistance, melt moldability and electrical properties. BACKGROUND ART Copolymers (hereinafter abbreviated as PFA) of fluoropropyl vinyl ether (hereinafter abbreviated as PPVE) have been produced, and are used in a wide range of industrial fields because of their excellent properties.

[0003] However, the copolymer has the following problems. First, the comonomer PPVE
At present, it is produced by reacting a dimer of hexafluoropropene oxide with an alkali metal salt and then thermally decomposing it.
The overall VE yield is low. Further PPVE
Is poor in polymerizability with TFE, so the utilization of PPVE, that is, the ratio of the amount of PPVE charged during polymerization is extremely low.
For example, according to JP-B-48-2223, PPVE
Utilization is only a few to 30%. For this reason, a method and a process for collecting expensive PPVE are required. Furthermore, there is also a loss of PPVE in this step, making the copolymer expensive.

On the other hand, British Patent No. 812116 discloses a homopolymer of a monomer represented by CF ₂ ＣＦCF-OR (where R is an alkyl radical or a fluorinated alkyl radical) and a copolymer with TFE. It is shown. However, the CF ₂ described in this British Patent
= The copolymerization method of CF-OR and TFE is an emulsion polymerization method using water as a medium. The inventors have confirmed that when the copolymerization of CF ₂ ＣＦCF—OR and TFE is carried out by emulsion polymerization, the obtained copolymer is CF ₂ ＣＦCF
Despite the introduction of about 6 mol% of monomer units based on -OR, the same melting point as that of the homopolymer of TFE (32
7 ° C.), and the tensile strength of a sheet obtained from this copolymer was as low as 200 kg / cm ² .

Accordingly, an object of the present invention is to provide a method for producing a novel fluorine-containing copolymer having a high utilization rate of a monomer and having characteristics such as chemical resistance, mechanical strength, and heat resistance.

[0006]

DISCLOSURE OF THE INVENTION In view of the above-mentioned problems, the present inventors have considered that a fluorine-containing vinyl ether compound having good copolymerizability in a wide composition with a fluorine-containing olefin, particularly TFE, and having a high utilization factor. A large number of compounds were synthesized in order to search for and the copolymerization experiment was repeated. As a result, the fluorine-containing vinyl ether having a specific structure had good copolymerizability with TFE, and most of the fluorine-containing vinyl ether was copolymerized in a short time and in one polymerization. Polymerization was found. They have found that the copolymer obtained by solution polymerization is excellent in chemical resistance, mechanical strength and heat resistance and also excellent in melt moldability, and have completed the present invention.

That is, in the present invention, tetrafluoroethylene and the general formula CF ₂ ＣＦCFOCH ₂ (CF ₂ ) _n X [where X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. Is dissolved in an organic solvent to control the monomer composition ratio substantially constant in the presence of a fluorine-containing radical polymerization initiator, and the obtained copolymer is represented by the following general formula [A]: I]

[I]

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90 to 99.5 mol% of a monomer unit represented by the following formula (B):

[II]

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Wherein X is a hydrogen atom or a halogen atom, and n is an integer of 1 or more. Having a melt viscosity of 10 ² to 10 ⁷ poise and a melting point of 290 to 3 at 350 ° C.
A method for producing a fluorine-containing random copolymer, which is characterized in that polymerization is performed at 25 ° C.

In the monomer unit represented by the general formula [II], X may be a hydrogen atom or a halogen atom, and each halogen atom of fluorine, chlorine, bromine and iodine is employed. Further, n may be an integer of 1 or more, but n is 1 to 12, and 1 to 12, for ease of production of the fluorine-containing random copolymer of the present invention, that is, for ease of polymerization. 8
Is preferably within the range.

The composition of each monomer unit represented by the general formulas [I] and [II] is such that the monomer unit represented by the general formula [I] is 90 to 99.5 mol%. General formula [I
The monomer unit represented by I] is 0.5 to 10 mol%. When the amount of the monomer unit represented by the general formula [II] is less than 0.5 mol, melt moldability is deteriorated. On the other hand, when the amount of the monomer unit represented by the general formula [II] exceeds 10 mol%, the mechanical strength gradually decreases.
A solid copolymer is not obtained and becomes oily.

In the fluorine-containing random copolymer obtained according to the present invention, the monomer units represented by the aforementioned general formulas [I] and [II] are randomly arranged.

Since the fluorine-containing random copolymer obtained by the present invention is insoluble in various solvents, its molecular weight cannot be determined by ordinary means. However, according to the present invention
Since the melt viscosity of the obtained fluorine-containing random copolymer depends on the content and the molecular weight of the monomer unit represented by the general formula [II], the molecular weight can be estimated from the melt viscosity.

The melt viscosity of the fluorine-containing random copolymer obtained according to the present invention varies depending on the composition of each monomer unit represented by the general formulas [I] and [II]. For example, when the monomer unit represented by the general formula [II] is in the range of 0.5 mol% to 10 mol%, the melt viscosity measured at 350 ° C. is in the range of 10 ² to 10 ⁷ poise, 290-325 ° C, preferably 290-320 ° C. The melting point of the copolymer obtained by emulsion polymerization was 32.
Since the temperature is 7 ° C., the fluorine-containing random copolymer obtained by the present invention is clearly distinguished from the copolymer obtained by emulsion polymerization. Further, the fluorine-containing random copolymer obtained by the present invention having the above composition has a thermal decomposition temperature of 370 to 41.
It is in the range of 0 ° C.

The fluorine-containing random copolymer obtained according to the present invention has a —CH ₂ — group at around 2990 cm ⁻¹ in the infrared absorption spectrum (hereinafter referred to as IR), and 9
A —CH ₂ OCF ₂ — group near 00 cm ⁻¹ , and 1200 c
It has an absorption band based on the group, - m -CF ₂ around ^-1
Check the absorption band of this, such as, by quantifying, in the present invention
The content of the monomer unit based on the fluorinated vinyl ether represented by the general formula [II] can be determined as the fluorinated random copolymer obtained from the above.

FIG. 3 shows the IR of the fluorine-containing random copolymer film (50 μm thickness) obtained in Example 1.

Further, the structure of the side chain can be confirmed from a fragment generated by decomposition of the side chain by pyrolysis gas chromatography-mass spectrometry (hereinafter referred to as Py-GC / MS). For example, for the fluorine-containing random copolymer obtained in Example 1, a fragment derived from a pentafluoropropyl group can be detected from Py-GC / MS.

As the production method of the present invention , the following method is preferred.
Appropriately adopted .

That is, tetrafluoroethylene and the general formula [III] CF ₂ ＣＦCFOCH ₂ (CF ₂ ) _n X [III] [where X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. Is dissolved in an organic solvent and copolymerized in the presence of a radical polymerization initiator.

Specific examples of the fluorine-containing vinyl ether represented by the above general formula [III] used in the present invention are as follows.

CF ₂ ＣＦCFOCH ₂ CF ₃ , CF ₂ ＣＦCFO
_{CH 2 CF 2 CF 3, CF} 2 = CFOCH 2 CF 2 CF 2 H, CF 2 = CFOCH 2 (CF 2) 2 CF 3, CF 2 = CFOCH 2 (CF 2) 3 CF 3, CF 2 = CFOCH 2 ( _{CF 2) 4 CF 3, CF} 2 = CFOCH 2 (CF 2) 5 CF 3, CF 2 = CFOCH 2 (CF 2) 6 CF 3, CF 2 = CFOCH 2 (CF 2) 7 CF 3, CF 2 = CFOCH ₂ CF ₂ Cl, CF ₂ = CFOCH ₂ C
F ₂ Br, CF ₂ ＣＦCFOCH ₂ CF ₂ CF ₂ Br, CF ₂ ＣＦCFOC
_{H 2 CF 2 CF 2 Cl,} CF 2 = CFOCH 2 (CF 2) 2 CF 2 Br, CF 2 = CFOCH 2 (CF 2) 2 CF 2 Cl, CF 2 = CFOCH 2 (CF 2) 3 CF 2 Br, _{CF 2 = CFOCH 2 (CF 2} ) a ₃ CF ₂ Cl and the like.

Next, the above-mentioned fluorine-containing vinyl ether and T
Copolymerization with FE is performed. As a copolymerization method, solution polymerization performed by dissolving the above two monomers in an organic solvent is employed.

In this method, by controlling the monomer composition to be substantially constant, the composition of each monomer unit in the obtained copolymer can be made substantially the same as the monomer composition. As a method of keeping the monomer composition during polymerization substantially constant, a method in which the monomer is not supplied during the polymerization and the polymerization is performed with the monomer composition charged before the polymerization, or the same composition as the monomer composition charged before the polymerization is used. A method of supplying a monomer during polymerization is employed.

In the polymerization, 0.3 to 3 parts of the organic solvent in the solution in which each monomer is dissolved to remove the heat of polymerization is added.
The polymerization can be carried out in the presence of 10 times by weight, preferably 1 to 5 times by weight of water. Of course, since TFE is usually a gas, it is preferable to pressurize and supply the TFE to the gas phase of the polymerization reactor during polymerization.

The organic solvent used in the present invention is not particularly limited, but chlorofluorocarbons and perfluoro compounds are generally preferably used.

For example, trichlorotrifluoroethane,
Fluorinated solvents such as dichlorotetrafluoroethane, trichlorofluoromethane, dichlorodifluoromethane, perfluorocyclohexane, perfluorocyclobutane, perfluorotributylamine, perfluorotriamylamine and perfluoropolyethers are preferred.
When the polymerization method is specifically exemplified, a deoxygenated organic solvent and a fluorine-containing vinyl ether are added to a pressure vessel equipped with a stirrer and a thermometer. The proportion of these additions is selected in such a range that the viscosity rises with the progress of the polymerization, making it difficult to stir or that the heat of polymerization cannot be removed due to insufficient stirring, making it difficult to maintain the polymerization. . Usually, an organic solvent 10
0.1 to 3 parts by weight of fluorine-containing vinyl ether per 0 parts by weight
It is preferable to select from 0 parts by weight, preferably from 1 to 10 parts by weight. Further, water can be allowed to coexist in order to facilitate removal of the heat of polymerization and stirring.

Next, in order to deoxygenate the inside of the reaction vessel, for example, the operation of cooling and solidifying the contents of the reaction vessel and then deaeration is repeated. Thereafter, TFE is added to the gas phase of the reaction vessel. A radical generator as a polymerization initiator is dissolved in an organic solvent and added, and then TFE is pressurized to a predetermined pressure, and polymerization is performed while maintaining the temperature at the polymerization temperature.

The polymerization time varies depending on the pressure of TFE, the amount of the radical generator added, and the like.

The polymerization initiator used in this method is a fluorine-containing radical polymerization initiator, for example, a dialkyl peroxide-based, diacyl peroxide-based, peroxydicarbonate-based and azo-based one. In consideration of the heat resistance of the copolymer generally obtained, a perfluoro radical generator is preferred. For example, a fluorine-containing diacyl peroxide represented by the following formula is preferably used.

[0032]

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Wherein Z is -H, -F or -Cl, and y is an integer of 1 to 5. ]

[0034]

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Wherein Z and y are the same as those in the above formula,
q is an integer of 0-3. Examples of radical generators that can be suitably used in the present invention are as follows.

[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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The amount of the radical generator used cannot be determined unconditionally depending on the solvent used, the polymerization conditions, especially the polymerization temperature, but is usually 0.5 to 20 mol%, preferably 0.5 to 20 mol%, based on the fluorine-containing vinyl ether used for the polymerization. 1 to 10 mol%
May be added at the time of charging or intermittently. Depending on the conditions, the polymerization may be difficult to proceed. In such a case, it is effective to add the radical generator again during the polymerization.

The pressure of TFE is 1 kg / cm ² G to 30 k
The polymerization reaction proceeds sufficiently within the range of g / cm ² G, but the preferable pressure is 1 kg / cm ² G to 10 kg / cm ^2.
G. When TFE pressure is low, generally TFE
In contrast, when the pressure is high, the TFE content increases, and the production rate of the copolymer increases. Of course, the polymerization proceeds even if the pressure exceeds the lower limit value or the upper limit value. However, when the pressure is too high, there is a disadvantage that the apparatus becomes considerably expensive. The temperature at the time of polymerization is determined based on the decomposition rate of the radical generator used as one standard, and is usually 0 ° C.
About 100 ° C, preferably about 5 ° C to 80 ° C.
In particular, in a fluorine-containing or perfluoro-based diacyl peroxide having a high decomposition rate even at a low temperature, 5
C. to 60.degree. C. are preferred.

In the present invention, by performing copolymerization in the presence of a chain transfer agent, the tensile strength of the obtained fluorine-containing random copolymer is improved, and the melt viscosity is lowered.
This tendency is remarkable when the monomer unit represented by the general formula [II] is in the range of 0.5 mol% to 10 mol%. Examples of the chain transfer agent used in the present invention include alcohols such as methanol and ethanol; ethers such as dimethyl ether, methyl ethyl ether and diethyl ether; alkanes such as methane, ethane, propane and butane. Of these, alcohols and alkanes are preferred from the viewpoints of solubility in the polymerization solvent, safety of the produced copolymer, and the like. If the chain transfer agent is a gas, it may be injected at a pressure that can maintain a necessary amount of dissolution in the solvent for polymerization. In the case of a liquid, the required amount may be added in advance or intermittently. The amount of the chain transfer agent used varies slightly depending on the type and polymerization conditions, but is usually 0.05 to 10 mol%, preferably 0.1 to 10 mol%, based on the total amount of the added monomers.
1-5 mol% is preferred. If the amount of the chain transfer agent is less than this range, the effect of improving the tensile strength is not obtained, or even if it is, the decrease in the melt viscosity is small. Conversely, if the amount is too large, the tensile strength will rather decrease.

Accordingly, the present invention relates to a method for preparing tetrafluoroethylene and the general formula CF ₂ ＣＦCFOCH ₂ (CF ₂ ) _n X wherein X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. Is dissolved in an organic solvent and copolymerized in the presence of a fluorine-containing radical polymerization initiator and a chain transfer agent in an amount of 0.1 to 5 mol% based on the total amount of the monomers, to obtain a compound represented by the general formula [ II], wherein the monomer unit represented by the formula [II] is in the range of 0.5 mol% or more and 10 mol% or less.

Further, a fluoroolefin such as hexafluoropropylene, chlorotrifluoroethylene, or vinylidene fluoride may be added to TFE in order to modify the properties of the obtained copolymer. In general, it is preferable to use 5 mol% or less based on TFE.

The produced copolymer is recovered by separating the organic solvent (and water) from the polymerization mixture. In this case, water can be easily separated from the copolymer by filtration, but the organic solvent has a high concentration of the copolymer dispersed therein and may not be recovered by filtration. In such a case, the copolymer can be recovered by using a centrifuge or by separating the copolymer from the solvent under reduced pressure.

The fluorine-containing vinyl ether used in the present invention copolymerizes well with TFE, and the pressure during the polymerization of TFE is 1
If it is at least kg / cm ^2, it can be almost copolymerized in a short time and the conversion can be made 100%. In such a case, fluorinated vinyl ether is hardly detected in the organic solvent used for the polymerization. Therefore, the step of recovering the fluorinated vinyl ether becomes unnecessary. Although it has already been mentioned that conventional PPVE has a poor copolymerizability when copolymerized with TFE and requires a recovery step, this is one of the great advantages of the above production method. One.

[0048]

The fluorine-containing random copolymer obtained by the present invention contains 0.5 to 10 mol% of a monomer unit based on a fluorine-containing vinyl ether represented by the general formula [II].
Although the copolymer contained hydrogen atoms in the molecule, there was a concern that the chemical resistance was inferior, but in fact the chemical resistance was surprisingly very good, and it was commercially available as a copolymer of PPVE and TFE. Comparable to existing PFA and other perfluoro resins.
Therefore, it can be used as a film, a tube, a packing material, a lining material, and other molded products in an industrial field requiring chemical resistance. It also has excellent electrical properties, and in electrical and electronics fields connectors, substrate materials,
It can be used for insulating materials and others.

A copolymer containing 0.5 to 10 mol% of a monomer unit based on a fluorine-containing vinyl ether represented by the general formula [II] has a higher tensile strength than PFA which is a conventional copolymer of PPVE and TFE. It is a molding material excellent in mechanical properties such as, and can be used in a wide range of fields as a molded product.

The molded product of the copolymer film, tube or the like obtained by the present invention has heat shrinkability, and can be used as a heat shrinkable tube or film. Further, by introducing crosslinking, it is useful as a highly fluorinated fluororubber.

[0051] Also without causing cleavage of the main chain found in the fluorination of conventional hydrocarbon polymer by fluorinating a fluorine-containing random copolymer obtained by the present invention fluorinating agent, for example, F ₂ Can be fluorinated in high yield. Therefore, the copolymer obtained by the present invention is
It is also useful as a raw material for a perfluoro copolymer.

[0052]

The present invention will be described in detail with reference to the following examples.

The measured values were obtained as follows.

1. Mechanical Properties (i) Measurement of Yield Strength, Tensile Strength and Elongation According to JIS K7113 (ii) Preparation of Test Samples The fluorinated copolymer powder obtained according to the present invention and a commercially available PFA powder and pellets for comparison were prepared. 350 ° C
Press under the temperature of to create a sheet of 1-2mm thickness,
Test pieces required for the above test method were prepared.

2. Thermal properties Thermal decomposition temperature, melting point Thermoflex (R-TG-DT
A: Rigaku Denki Co., Ltd.) at a heating rate of 5 ° C./mi
n, measured under a nitrogen stream.

3. Measurement of melt viscosity A Koka type melt viscosity measuring device was used.

A die having a diameter of 0.5 mm and a length of 5 mm
And a load of 50 kg / cm ² was used for the measurement.

Example 1 In a 3 liter stainless steel autoclave equipped with a stirrer, 1,1,2-trichloro-1, purified by distillation in advance.
1 liter of 2,2-trifluoroethane, CF ₂ ＣＦCFOCH ₂
10 g of CF ₂ CF ₃ and (CF ₃ CF _2.
1,1,2-trichloro-1,2,2 containing 1 g of CO ₂ ) ₂
10 cc of 2-trifluoroethane was added. After cooling the autoclave with liquid oxygen and solidifying the content, the autoclave was evacuated with a vacuum pump. Further, nitrogen was introduced to a pressure of 3 kg / cm ^{2, and} the temperature was raised (about −5 ° C.) while maintaining the pressure until the contents were dissolved. This operation was repeated three times to remove oxygen in the autoclave. Again, after cooling and solidifying with liquid oxygen and degassing with a vacuum pump, the temperature was raised, and when it reached about 15 ° C., TFE was introduced at a pressure of 3 kg / cm ² G,
After the TFE was dissolved in saturation, the TFE introduction valve was closed. The temperature of the autoclave was raised to 20 ° C. to initiate polymerization. When the polymerization was continued for 5 hours, the pressure in the autoclave dropped almost to the vapor pressure of trichlorotrifluoroethane, so the polymerization was stopped. After that, the autoclave was connected to a vacuum pump via a trap for cooling and collecting the solvent and unpolymerized CF ₂ ＣＦCFOCH ₂ CF ₂ CF _3, and the pressure was reduced while stirring the inside of the autoclave. Vinyl ether was collected in the trap. After the solvent was completely removed, the autoclave was opened and a white powdery copolymer was formed. When the obtained copolymer was dried under reduced pressure at 150 ° C. for 10 hours, about 150 g of the copolymer was obtained.

When the recovered solvent was analyzed by gas chromatography, unpolymerized CF ₂ ＣＦCFOCH ₂ CF ₂
CF ₃ was not detected, and the charged CF ₂ = CFOCH ₂ CF ₂
It was found that CF ₃ was polymerized at almost 100% conversion. The conversion of TFE calculated from the pressure change was about 97%. 400 ° C. by pyrolysis gas chromatography mass spectrometry (hereinafter abbreviated as Py-GC / MS)
As a result of analyzing the decomposition product at
Structure of the side chain from the F ₃ CF ₂ CH and CF ₃ CF ₂ CH ₃ was detected was confirmed to be -OCH ₂ CF ₂ CF _3. From this result and the measurement result of IR, 3.1 mol%

[0060]

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It was found that the monomer unit represented by the formula (1) was contained in the copolymer, which was equivalent to 3.0 mol% of the composition at the time of preparation.

Examples 2 to 4 Using the polymerization apparatus and method of Example 1, fluorine-containing copolymers having different compositions were synthesized. Table 1 shows the conditions, conversion of the monomers, and the analysis values of the obtained copolymer together with the values of Example 1 which were different from those of Example 1.

[0063]

[Table 1]

Example 5 In a 300 ml autoclave, CF ₂ ＣＦCFOCH ₂ (C
4.1 g of F ₂ ) ₂ CF ₃ and 1,1,2-
Trichloro-1,2,2-trifluoroethane 150m
1 and the same deoxygenation operation as in Example 1 was performed. Thereafter, TFE was introduced at a pressure of 6 kg / cm ² G, and after the TFE was saturated and dissolved, the TFE supply valve was closed. After adjusting the temperature of the autoclave to 20 ° C., the polymerization initiator (CF
5 ml of a trichlorotrifluoroethane solution containing 0.15 g of ₃ CF ₂ CF ₂ CO ₂ ) ₂ was injected.

When the polymerization was continued for 5 hours, the pressure in the autoclave dropped to about the vapor pressure of the solvent. When the solvent was distilled off under reduced pressure according to the procedure of Example 1, a white powdery copolymer was obtained.

When the recovered solvent was analyzed by gas chromatography, CF ₂ ＣＦCFOCH ₂ (CF ₂ ) ₂ .CF ₃ was hardly detected, and the conversion was almost 100%. It was also found from the pressure change that TFE had a conversion of almost 100%.

On the other hand, the obtained copolymer was heated at 150 ° C. for 10 hours.
The product dried under reduced pressure for a period of time was analyzed by Py-GC / MS and IR.

[0068]

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A monomer unit represented by the following formula was contained, which corresponded to 1.45 mol% of the monomer composition at the time of preparation.

Example 6 CF ₂ = CFOCH ₂ CF was placed in a 300 ml autoclave.
1.6 g of ₂ CF ₂ Cl, 150 ml of 1,1,2-trichloro-1,2,2-trifluoroethane as a solvent and 0.5 g of (CF ₃ CF ₂ .CO ₂ ) ₂ as a polymerization initiator were added.
Deoxygenation was carried out by the operation used in Example 1, and TFE was adjusted to 3.0.
After introducing at a rate of kg / cm ² G and dissolving in a saturated state, supply of TFE was stopped and polymerization was carried out at 20 ° C. for 5 hours.

The obtained white powder copolymer was Py-G
2.7 mol% of C / MS and IR analysis

[0072]

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It was found to contain the monomer unit represented by the following formula. This almost coincided with the monomer composition at the time of charging.

When the conversion of the monomer was measured,
TFE and fluorine-containing vinyl ether were almost 98%.

Example 7 Polymerization was carried out in the same manner as in Example 1 except that 7.8 g of CF ₂ ＣＦCFOCH ₂ CF ₃ was used. When polymerization was carried out for 4 hours, the polymerization was almost completed. When the conversions of the fluorinated alkyl vinyl ether and TFE were determined in the same manner as in Example 1, all were approximately 98%. When the obtained copolymer was dried under reduced pressure, it was about 145 g.

The copolymer obtained was analyzed and found to have a content of 3.0 mol%.

[0077]

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The monomer unit of the present invention was almost the same as the charged composition.

Example 8 The thermal decomposition temperature, the melt viscosity and the melting point of the fluorinated random copolymers obtained in Examples 1 to 7 were measured at 300 ° C., and the results are shown in Table 2. Also, the yield strength, tensile strength and elongation of each fluorine-containing random copolymer were measured,
The results are also shown in Table 2.

[0080]

[Table 2]

Reference Example 1 Each of the fluorine-containing random copolymers obtained in Examples 1 to 7 was tested for chemical resistance. The results are shown in Table 3.

[0082]

[Table 3]

Example 9 Using the apparatus of Example 1, copolymerization was carried out while changing the polymerization initiator, the fluorine-containing vinyl ether and the chain transfer agent. Table 4 shows the tensile strength, melting point, melt viscosity and thermal decomposition temperature of the obtained copolymer. The content of the fluorinated vinyl ether units in the copolymer was about 3 mol% in each case.

[0084]

[Table 4]

Example 10 A copolymer was synthesized using the apparatus method and the like of Example 1 except that methanol was added as a chain transfer agent and the conversion of polymerization was changed to 85%. The tensile strength, melt viscosity and melting point of the coalesced were measured. The content of the fluorinated vinyl ether units in the copolymer was about 3 mol% in each case.
Met.

[0086]

[Table 5]

Example 11 In Example 10, copolymerization was performed using ethane as a chain transfer agent instead of methanol, and the tensile strength and melt viscosity of the obtained copolymer were measured. The results obtained are shown in Table 7. The content of the fluorinated vinyl ether units in the copolymer was about 3 mol% in each case.

[0088]

[Table 6]

Example 12 To obtain a copolymer composition curve, tetrafluoroethylene was copolymerized with 2,2,3,3,3-pentafluoropropyl trifluorovinyl ether. Freon 113
Was used as a solvent, and (C ₂ F ₅ .COO) ₂ was used as a polymerization initiator. Polymerization initiator concentration 0.3 to 1 mol% (based on all monomers), pressure of tetrafluoroethylene 1 to 3 kg /
cm ² G, polymerization temperature 20 ° C., monomer conversion rate 5-20
Polymerization experiments were performed in mole%. Feynman-Ross (Fi
The copolymer composition curve was determined in accordance with the Neman-Ross method. The results obtained are shown in FIG. For comparison, a copolymer composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene was calculated using the copolymerizability ratio described in "Zurnal Priclado Heimya, 1984, 57 (5), 1126-8". . The results are shown in FIG.

Comparative Example 1 An autoclave equipped with a 500 cc stirrer was subjected to deoxygenation in 150 ml of water, CF ₂ ＣＦCFOCH ₂ CF ₂ CF ₃
4.2 g, ammonium perfluorooctanoate 0.1 g as an emulsifier, (NH ₄ ) ₂ S ₂ O as a polymerization initiator
₈ 0.2 g was added. After the system was deoxygenated, 6 kg / cm ^{2 of} tetrafluoroethylene was injected. The temperature of the autoclave was set to 60 ° C., and the polymerization was carried out for 8 hours while maintaining the pressure of tetrafluoroethylene at 6 kg / cm ² . After the polymerization, the mixture was filtered and dried to obtain 29 g of a white powder.
When a film was formed by hot pressing and the infrared absorption spectrum was measured, about 6 mol% of CF ₂ ＣＦCFOCH _{2 was obtained.}
CF ₂ CF ₃ was included. The melting point in the obtained copolymer was 327 ° C., and the tensile strength was 200 kg / cm ² . The melt viscosity was 7 × 10 ⁶ poise and the glass transition temperature was 130 ° C.

[Brief description of the drawings]

FIG. 1 is a copolymer composition curve in copolymerization of 2,2,3,3,3-pentafluoropropyltrifluorovinyl ether and tetrafluoroethylene.

FIG. 2 is a copolymer composition curve of perfluoropropyl vinyl ether and tetrafluoroethylene.

FIG. 3 is an infrared absorption spectrum of the fluorine-containing random copolymer obtained in Example 1.

Claims (2)

(57) [Claims] (1) tetrafluoroethylene and a compound represented by the general formula: CF ₂ ＣＦCFOCH ₂ (CF ₂ ) _n X, wherein X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. And a fluorine-containing vinyl ether represented by the general formula [A], wherein the monomer composition ratio is controlled to be substantially constant in the presence of a fluorine-containing radical polymerization initiator in the presence of a fluorine-containing radical polymerization initiator. I] embedded image [I] And (B) a monomer unit represented by the following general formula [II]: [Where X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. The monomer unit represented by the formula:
5 mol%, and the melt viscosity measured at 350 ° C. is 10
^2-10 is ⁷ poises, process for producing a fluorinated random copolymer having a melting point characterized by polymerizing such that two hundred and ninety to three hundred and twenty-five ° C.. 2. A compound of the general formula CF ₂ ＣＦCFOCH ₂ (CF ₂ ) _n X wherein X is a hydrogen atom or a halogen atom, and n is 1
Is an integer greater than or equal to. Is dissolved in an organic solvent and copolymerized in the presence of a fluorine-containing radical polymerization initiator and a chain transfer agent in an amount of 0.1 to 5 mol% based on the total amount of monomers. The method for producing a fluorine-containing random copolymer according to claim 1.